Plasma processing equipment and plasma processing method

Abstract

Provided are plasma processing equipment and a plasma processing method which are capable of measuring reflected light reflected from a region to be processed, regardless of the pattern layout of a device. This plasma processing equipment includes: a light irradiation unit that has a plurality of irradiators which emit light toward different positions on the surface of a wafer placed on a sample stage; a light receiving unit that receives reflected light, which is the light emitted from the plurality of irradiators and reflected by the wafer; and a processing amount detection unit that detects the processing amount of the wafer on the basis of information obtained from the reflected light received by the light receiving unit during processing of the wafer. The processing amount detection unit selects an irradiator for performing light irradiation from among the plurality of irradiators on the basis of the difference between information on each reflection position of the wafer at which the light emitted from each of the plurality of irradiators is reflected and information on a processing position of the wafer, and detects the processing amount of the wafer using the thus-selected irradiator.

Description

Plasma processing apparatus and plasma processing method

[0001] The technology of the present disclosure relates to a plasma processing apparatus and a plasma processing method using the same.

[0002] A semiconductor device, for example, has various components and interconnections on the surface of a wafer, and is formed by repeatedly depositing films of various materials, such as conductors, semiconductors, and insulators, and then removing unnecessary portions.

[0003] Dry etching using plasma is widely used as a process for removing unwanted portions. In plasma etching, gas introduced into the processing chamber of an etching device is converted into plasma using a high-frequency power source, and the wafer is then exposed to the plasma gas to etch the wafer.

[0004] Anisotropic and isotropic etching are performed by sputtering with ions in the plasma, chemical reactions with radicals, etc. By using these etching methods, components and wiring with various structures can be formed on the surface of the wafer.

[0005] If the processed shape of the wafer by plasma etching differs from the design, the various components formed will not be able to function as intended. Therefore, many process monitor technologies have been proposed to monitor and stabilize the wafer etching process.

[0006] For example, a process monitor that measures the thickness of a film formed on a wafer or the depth of a groove or hole formed on the wafer by measuring the light reflected from the wafer during etching processing is also called a film thickness / depth monitor, and is used to determine the endpoint of the etching process, etc. In the following, we will abbreviate film thickness / depth monitor and simply call it a film thickness monitor.

[0007] Patent Document 1 describes a method for improving processing accuracy using a film thickness monitor. More specifically, Patent Document 1 describes a method for detecting the timing immediately before the film to be processed is completely removed using a film thickness measurement device equivalent to a thick film monitor using plasma light as a light source, thereby terminating the etching process, and then switching to conditions for highly selectively etching the processed portion and the non-processed portion.

[0008] Furthermore, Patent Document 2 describes a technology for improving the measurement accuracy of film thickness and depth by a film thickness monitor. More specifically, Patent Document 2 describes that by using an external light source instead of plasma light as the light source for irradiating the wafer, the light source fluctuation of the light source is reduced, thereby enabling highly accurate film thickness and depth measurements to be realized.

[0009] JP 2006-119145 A JP 2004-507070 A

[0010] In the manufacture of semiconductor devices, electronic circuits and wiring that perform various functions, as well as the boundaries between devices, are formed on wafers in a specific layout to create devices that achieve the desired functions. For example, a memory device has a memory section that stores data and a circuit section that stores and erases that data. Logic devices also have an arithmetic section that calculates digital data and a memory section that temporarily stores the calculation results. The layout of the sections where these electronic circuits are formed and the boundaries of the devices vary depending on the device. In the following, these layouts on wafers will be collectively referred to as pattern layouts.

[0011] Since there are various pattern layouts as described above, in order to determine the end point using a film thickness monitor and achieve high-precision processing in the device manufacturing process, it is preferable to measure the reflected light reflected from the processing target area being processed in that process. For example, in the memory cell formation process for a memory device, it is preferable to obtain the reflected light from the memory cell area, which is the processing target area, rather than the boundary area of ​​the device or the circuit area for recording and erasing data.

[0012] In a film thickness monitor that irradiates a wafer with light from an external light source through a light irradiation port (also referred to as an irradiator) and measures the reflected light received through a light measurement port (also referred to as a light receiving unit), if the positions of the light irradiation port and the light measurement port are fixed, the position on the wafer where the reflected light is measured is uniquely determined and is a fixed position. Specifically, the position where the perpendicular bisector of the line segment connecting the two ports intersects with the wafer is the center of the monitor position where the reflected light is measured.

[0013] When using a film thickness monitor in which the positions of the light irradiation port and the light measurement port are fixed, it is difficult to constantly measure the light reflected from the processing target area of ​​the wafer in the manufacturing process of devices with various pattern layouts. Therefore, depending on the pattern layout of the device on the wafer, the accuracy of measuring the film thickness and depth on the wafer by the film thickness monitor may decrease, making it difficult to accurately determine the endpoint using the film thickness monitor.

[0014] The technology disclosed herein has been made in consideration of the above circumstances, and aims to provide a plasma processing apparatus and a plasma processing method that can measure reflected light reflected from a processing target area regardless of the pattern layout of the device.

[0015] A representative example of the techniques disclosed herein is a plasma processing apparatus comprising a processing chamber inside a vacuum vessel and a sample stage disposed in the processing chamber and on which a wafer to be processed is placed, the plasma processing apparatus comprising: a light irradiation unit having a plurality of irradiators that irradiate light at different positions on the surface of the wafer placed on the sample stage; a light receiving unit that receives light reflected by the wafer from the light irradiated from the plurality of irradiators; and a processing amount detection unit that detects the processing amount of the wafer based on information obtained from the reflected light received by the light receiving unit during processing of the wafer, the processing amount detection unit determining which irradiator from the plurality of irradiators will irradiate light based on the difference between information on each reflection position on the wafer where light irradiated from each of the plurality of irradiators is reflected and information on the processing position of the wafer, and detecting the processing amount of the wafer using the determined irradiator.

[0016] The effects obtained by representative techniques of the present disclosure can be briefly explained as follows. The technique of the present disclosure makes it possible to always measure reflected light from the processing target area regardless of the wafer pattern layout. As a result, highly accurate film thickness measurement and endpoint determination can be achieved. Ultimately, highly accurate device processing can be achieved. Issues, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0017] 1 is a diagram showing the overall configuration of a plasma processing apparatus according to embodiment 1. FIG. 2 is a diagram showing a schematic configuration of a wafer processing device according to embodiment 1. FIG. 3 is a diagram showing a schematic configuration of an optical system according to embodiment 1. FIG. 4 is a diagram showing a schematic example of a pattern layout of a wafer in embodiment 1. FIG. 5 is a diagram showing functional blocks of a processing amount calculation unit according to embodiment 1. FIG. 6 is a diagram showing a spectrum of reflected light from an electronic circuit unit of a wafer in embodiment 1. FIG. 7 is a diagram showing a spectrum of reflected light from a peripheral portion of a wafer in embodiment 1. FIG. 8 is a diagram showing a schematic positional relationship between a light irradiation unit and a light receiving unit according to embodiment 2. FIG. 9 is a diagram showing a wafer processing position and a monitor position in embodiment 2. FIG. 10 is a diagram showing a schematic positional relationship between a light irradiation unit and a light receiving unit according to embodiment 3. FIG. 11 is a diagram showing an example of a wafer processing position and a monitor position in embodiment 3. FIG. 12 is a diagram showing a spectrum of reflected light obtained by test irradiation in embodiment 4. FIG. 13 is a diagram showing an example of a calculation result of an error value between the spectrum of reflected light at each monitor position and a reference spectrum in embodiment 6.

[0018] Hereinafter, embodiments of the technology of the present disclosure will be described in detail with reference to the drawings. In the drawings, identical parts are generally designated by the same reference numerals, and repeated explanations will be omitted. In the drawings, components may be depicted schematically in terms of width, thickness, shape, etc., compared to the actual embodiment in order to facilitate understanding of the invention. However, this is merely an example and does not limit the interpretation of the present disclosure.

[0019] (Embodiment 1) Fig. 1 is a diagram showing an outline of the overall configuration of a plasma processing apparatus according to embodiment 1. Fig. 2 is a diagram showing a schematic configuration of a wafer processing apparatus according to embodiment 1. Fig. 3 is a diagram showing a schematic configuration of an optical system according to embodiment 1.

[0020] As shown in FIG. 1, the plasma processing apparatus 100 according to this embodiment includes a wafer processor 200 that performs an etching process (plasma process) on a wafer 500 to be processed, and a processing amount measuring device 300 that measures the processing amount (etching amount) of the wafer 500 by the wafer processor 200.

[0021] <Wafer Processor> First, a schematic configuration of the wafer processor 200 will be described. As an example, the wafer processor 200 according to this embodiment uses a microwave electric field as an electric field for forming plasma, generates ECR (Electron Cyclotron Resonance) between the microwave electric field and magnetic field to form plasma, and uses the plasma to etch a processing object such as a semiconductor wafer (hereinafter simply referred to as a wafer). In other words, the wafer processor 200 can also be called a plasma etching apparatus.

[0022] 2, the wafer processor 200 has a container, such as a vacuum container 205, that includes a processing chamber 203 in which a plasma 201 is generated. In the processing chamber 203, below the space in which the plasma 201 is generated, a sample stage 207 is disposed on which a wafer 500 to be processed is placed.

[0023] The upper part of the processing chamber 203 is closed by, for example, a disk-shaped dielectric window member 209. A shower plate 211 that forms a circular ceiling surface of the processing chamber 203 is provided below the window member 209. The shower plate 211 has a disk shape with a plurality of gas introduction holes 211a that are arranged to penetrate through the center, and etching process gas is introduced into the processing chamber 203 through the gas introduction holes 211a.

[0024] An exhaust port 213 connected to the processing chamber 203 is provided at the bottom of the vacuum vessel 205. Also provided below the processing chamber 203 are a vacuum pump 215 such as a turbo molecular pump for exhausting gas from the processing chamber 203 to reduce the pressure, and an exhaust amount control valve 217 for adjusting the exhaust flow rate or speed by increasing or decreasing the area of ​​the flow path.

[0025] An electric field / magnetic field generating unit 219 that generates an electric field and a magnetic field for generating plasma 201 in the processing chamber 203 is disposed above the vacuum vessel 205. The electric field / magnetic field generating unit 219 includes a waveguide 221 and an electric field generating power supply 223. A high-frequency electric field generated from the electric field generating power supply 223 is transmitted through the inside of the waveguide 221 and introduced into the processing chamber 203.

[0026] A magnetic field generating coil 225 is disposed around the lower end of the waveguide 221 and around the vacuum vessel 205. The magnetic field generating coil 225 is composed of an electromagnet and a yoke that are supplied with a direct current to form a magnetic field.

[0027] In the wafer processor 200 configured as described above, microwaves are generated by the electric field generating power supply 223 while a processing gas is introduced into the processing chamber 203 through the gas inlet holes 211a of the shower plate 211. The microwave electric field is supplied from above to below into the processing chamber 203, passing through the window member 209 and the shower plate 211. Furthermore, a magnetic field generated by a direct current supplied to the magnetic field generating coil 225 is supplied into the processing chamber 203, where it interacts with the microwave electric field, generating ECR. This ECR excites, dissociates, or ionizes atoms or molecules of the processing gas, generating high-density plasma 201 in the processing chamber 203. The plasma 201 then performs an etching process (plasma processing) on ​​a semiconductor wafer 500 placed on the sample stage 207.

[0028] <Overall Control Unit> As shown in FIG. 1, the plasma processing apparatus 100 includes an overall control unit 150 that comprehensively controls the operation of the plasma processing apparatus 100 .

[0029] The overall control unit 150 is composed of, for example, a calculation unit such as a central processing unit (CPU), a random access memory (RAM) unit such as a semiconductor memory, a storage unit such as a solid state drive (SSD) or a hard disk drive (HDD), a communication unit, etc. Note that the overall control unit 150 may use an application specific integrated circuit (ASIC) or a programmable logic device (PLD) such as a field programmable gate array (FPGA) instead of a CPU.

[0030] The overall control unit 150 controls the operation of the wafer processor 200, which is a plasma etching apparatus, as one of the controls of the plasma processing apparatus 100. The overall control unit 150, for example, introduces gas into the processing chamber 203, generates and controls the plasma 201, and applies voltage to the wafer 500 using a high-frequency power source (not shown). In other words, the overall control unit 150 performs synchronization and timing adjustments between the various devices in the processing chamber 203 so that the desired etching process is performed on the wafer 500.

[0031] Furthermore, when the plasma 201 is pulsed, this pulsing control is also performed by the overall control unit 150. At this time, the application of voltage from a high-frequency power source or the like that converts the etching gas into plasma, modulation of microwave irradiation, etc. switches these on / off, thereby pulsing the plasma 201. The plasma 201 is also pulsed by modulation of the introduction time of the etching gas.

[0032] <Processing Amount Measuring Device> As described above, the plasma processing apparatus 100 is equipped with a processing amount measuring device 300 that measures the processing amount (etching amount) of the wafer 500 by the wafer processing device 200. This processing amount measuring device 300 is what can be called a film thickness monitor, which measures the thickness of a film formed on the wafer 500 and the depth of a groove or hole formed on the wafer 500.

[0033] The processing amount measuring device 300 has a light source unit 310, an optical system 320, and a detection unit 330. Note that, as an example, the light source unit 310, the optical system 320, and the detection unit 330 are arranged in the cavity 227, which is the space between the waveguide 221 and the window member 209 of the wafer processing device 200 described above. For example, the optical system 320 is arranged on the window member 209.

[0034] The light source unit 310 emits continuous light ranging from ultraviolet to infrared. However, when the processing amount measuring device 300 measures the processing amount using a specific wavelength, in other words, measures film thickness and depth, the light source unit 310 may be one that emits light of the specific wavelength.

[0035] The light emitted from the light source unit 310 is introduced into the processing chamber 203 via the optical system 320 and is irradiated onto the semiconductor wafer 500 as irradiation light 311 .

[0036] 3, the optical system 320 includes a light irradiation unit (also referred to as a multi-point irradiation port) 321. The light irradiation unit 321 includes a plurality of irradiators (also referred to as irradiation optical ports) 323 for irradiating the light emitted from the light source unit 310 into the processing chamber 203 as irradiation light 311.

[0037] Furthermore, the multiple irradiators 323 are disposed above the processing chamber 203 (for example, in the cavity 227) as described above, and are disposed at different positions in the in-plane direction of the wafer 500. As an example, the multiple irradiators 323 are disposed in a row in the radial direction of the wafer 500.

[0038] Although not shown, each illuminator 323 is configured to include a collimator lens and an optical fiber connected to the collimator lens and the light source unit 310. When irradiating the wafer 500 with the irradiation light 311, the light emitted by the light source unit 310 is introduced into one or more specific optical fibers. As a result, the irradiation light 311 is irradiated onto the wafer 500 via one or more illuminators 323.

[0039] The optical input from the light source unit 310 to each irradiator 323 is switched by a fiber switch (not shown) or the like. The configuration of the irradiator 323 is not particularly limited as long as it can irradiate the light emitted from the light source unit 310 as irradiation light 311 onto the wafer 500 in the processing chamber 203.

[0040] In addition, in the present embodiment, an example has been described in which the plurality of illuminators 323 are linearly arranged on a plane parallel to the wafer 500, but the arrangement of the illuminators 323 is not limited to this. The illuminators 323 may be arranged, for example, on a two-dimensional plane, or may be arranged in a three-dimensional space above the wafer 500.

[0041] Furthermore, the optical system 320 includes at least one light receiving unit (light receiving port) 325 for inputting the reflected light 312 reflected by the wafer 500 to the detection unit 330. In this embodiment, the optical system 320 includes one light receiving unit 325. Although not shown, this light receiving unit 325 includes a collimator lens and an optical fiber that connects the collimator lens and the detection unit 330.

[0042] The optical system 320 may include a plurality of light receiving units 325. In this case, each light receiving unit 325 includes a collimator lens and an optical fiber. In addition, when detecting the reflected light 312 from the wafer 500, the light received by a specific light receiving unit 325 is input to the detection unit 330. That is, the light from a specific optical fiber that constitutes the light receiving unit 325 is input to the detection unit 330.

[0043] Here, the reflected light 312 detected by the detection unit 330 is light reflected from the position where the perpendicular bisector of the line connecting the irradiator 323 emitting light and the light receiving unit 325 connected to the detection unit 330 intersects with the wafer 500. The reflection position on the wafer 500 of the reflected light 312 input to the light receiving unit 325 is referred to as the "monitoring position."

[0044] In this embodiment, the processing amount measuring device 300 has been illustrated as having an independent light source unit 310 and optical system 320, but the configuration of the processing amount measuring device 300 is not limited to this. In the processing amount measuring device 300, the light source unit 310 may be integrated with the optical system 320. For example, each of the irradiators 323 included in the optical system 320 may be configured to include an LED as a light source. In this case, in the processing amount measuring device 300, the light source unit 310 is configured to be included in the optical system 320.

[0045] Furthermore, in order to efficiently irradiate the wafer 500 with the irradiation light 311, each irradiator 323 may be configured by combining an LED and a collimator lens.

[0046] Furthermore, the throughput measuring device 300 may include, for example, a display-type light source having a specific size and number of pixels as the light irradiating unit 321. In this case as well, the light source unit 310 is configured to be included in the optical system 320.

[0047] The detection unit 330 includes, for example, a spectroscope, which separates the introduced light and detects the amount of light for each wavelength. When measuring the processing amount (film thickness and depth on the wafer 500) of the wafer 500 using a specific wavelength, the detection unit 330 is not limited to a spectroscope and may include a photodetector or the like.

[0048] In this case, if only the light of the desired specific wavelength is introduced into the detection unit 330, the detection unit 330 may be configured with only a photodetector. If continuous light is introduced, the detection unit 330 should be provided with a device that selects only the specific wavelength, such as a monochromator, located before the photodetector.

[0049] The detection unit 330 continuously detects light at regular intervals, for example, 2 Hz or 10 Hz, during plasma processing of the wafer 500. The detection data detected by the detection unit 330 is then transmitted to the processing amount detection unit 340.

[0050] Similar to the overall control unit 150, the processing amount detection unit 340 is composed of, for example, a calculation unit such as a CPU, a RAM unit, a storage unit, a communication unit, etc., and calculates the processing amount (etching amount) of the wafer 500. In this embodiment, the processing amount detection unit 340 includes a processing position information acquisition unit 341, an optical system condition determination unit 343, and a processing amount calculation unit 345.

[0051] The processing position information acquisition unit 341 acquires information (hereinafter also referred to as processing position information) relating to the processing position (also referred to as processing position) of the processing target wafer 500. As an example, the processing position information acquisition unit 341 acquires the processing position information of the wafer 500 from a processing information management unit (not shown) prior to the etching process.

[0052] Here, the information relating to the processing position on the wafer 500 is, for example, information such as coordinates of the processing position in the pattern layout of the wafer 500, or coordinates specifying the processing target region including the processing position.

[0053] 4 is a diagram schematically illustrating an example of a pattern layout of a wafer in embodiment 1. As shown in Fig. 4, a wafer 500 to be processed has, as a pattern layout, an individual pattern 505 including an electronic circuit section 501 and its peripheral section 503. This individual pattern 505 exists repeatedly on the wafer 500.

[0054] For example, the size of the electronic circuit section 501 is about 5 mm long and 15 mm wide. The size of the individual patterns 505, that is, the size up to the boundary between adjacent individual patterns 505, is about 30 mm long and 30 mm wide.

[0055] In the individual pattern 505 of the wafer 500, the electronic circuit section 501 is etched. That is, in the example shown in Fig. 4, the electronic circuit section 501 is the processing position or processing target area.

[0056] Therefore, the information supplied from the processing position information acquisition unit 341 to the optical system condition determination unit 343 is the coordinates of the processing position within this electronic circuit unit 501. The processing position information acquisition unit 341 supplies, for example, information on the coordinates of processing positions P11 to P14 within each electronic circuit unit 501 to the optical system condition determination unit 343.

[0057] The processing positions P11 to P14 can be set at any positions within the electronic circuit section 501, but are preferably set near the center of the electronic circuit section 501, for example.

[0058] The information acquired by the processing position information acquisition unit 341 is supplied to the optical system condition determination unit 343. The optical system condition determination unit 343 determines the conditions of the optical system 320 based on the processing position information on the wafer 500 supplied from the processing position information acquisition unit 341.

[0059] As one of the conditions of the optical system 320, the optical system condition determination unit 343 determines the irradiator 323 that will irradiate light from among the multiple irradiators 323 based on the difference between information on each reflection position (monitor position) on the wafer 500 where light irradiated from each of the multiple irradiators 323 is reflected and information on the processing position on the wafer 500, and detects the processing amount of the wafer 500 using the determined irradiator 323.

[0060] In this embodiment, the optical system condition determination unit 343 selects, from among the above-described plurality of irradiators 323, an irradiator 323 in which the distance between the reflection position (monitoring position) of the wafer 500 where the light irradiated from the irradiator 323 is reflected and the processing position of the wafer 500 is closer than a preset set distance. Note that the set distance may be set arbitrarily, but it is preferable to set it as short as possible.

[0061] The optical system condition determination unit 343 determines the conditions of the optical system 320 by comparing the coordinates specifying the processing position or processing target area of ​​the wafer 500 transmitted from the processing position information acquisition unit 341 with the coordinates of the monitor position selectable by the optical system 320.

[0062] 3, for example, reflected light 312A is irradiation light 311A ​​emitted from the illuminator 323 farthest from the light receiving unit 325 and reflected by the wafer 500. Also, reflected light 312B is irradiation light 311B emitted from the illuminator 323 closest to the light receiving unit 325 and reflected by the wafer 500.

[0063] As can be seen from this figure, by changing the light irradiation position in the light irradiation unit 321, that is, by changing the irradiator 323 used, the reflection position (monitoring position) on the wafer 500 of the reflected light 312 received by the light receiving unit 325 changes.

[0064] 3, 12 illuminators 323 are arranged at intervals of about 10 mm. In this case, by switching the illuminators 323 that emit light, the monitoring position of the reflected light 312 detected by the light receiving unit 325 can be controlled at intervals of about 5 mm. In other words, the optical system condition determination unit 343 can determine a desired illuminator 323 from among the multiple illuminators 323 whose monitoring positions differ at intervals of about 5 mm.

[0065] In this embodiment, the optical system condition determining unit 343, for example, identifies the monitor position whose coordinates are closest to the coordinates of the processing position on the wafer 500, and determines the irradiator 323 corresponding to the identified monitor position.

[0066] As an example, as shown in FIG. 4, assume that monitor positions P21 to P26 selectable by the optical system 320 exist within the individual pattern 505. In this case, the optical system condition determination unit 343 extracts the combination in which the distance between the coordinates of the processing positions P11 to P15, which are the processing position information, and the coordinates of the monitor positions P21 to P25 is closest. In this example, the combination of the monitor position P21 and the processing position P11 and the combination of the monitor position P24 and the processing position P13 are extracted. Then, the optical system condition determination unit 343 selects one of the monitor positions P21 or P24 and determines the irradiator 323 corresponding to the selected monitor position.

[0067] As described above, when coordinate information of a plurality of processing positions P11 to P14 is supplied from the processing position information acquisition unit 341, the optical system condition determination unit 343 may identify the monitor position of the coordinates closest to each of the processing positions P11 to P14, and determine one or more irradiators 323 to irradiate light so as to reach each of the identified monitor positions.

[0068] Furthermore, if the optical system 320 has multiple light receiving units 325 and the monitor position on the wafer 500 changes depending on the selection of the light receiving unit 325, the optical system condition determination unit 343 may select and determine the light receiving unit 325 in conjunction with the above-mentioned irradiator 323.

[0069] Furthermore, for example, when the processing position information of the wafer 500 is coordinates that identify the area to be processed, the optical system condition determination unit 343 may determine multiple irradiators 323 corresponding to multiple monitor positions included in the area to be processed as the irradiators 323 that will perform light irradiation.

[0070] The conditions of the optical system 320 determined by the optical system condition determining unit 343 in this manner are supplied to a processing amount calculating unit 345 .

[0071] The processing amount calculation unit 345 calculates the processing amount (etching amount) of the wafer 500 using the specific irradiator 323 based on the information supplied from the optical system condition determination unit 343. For example, by controlling the state of the optical system 320, the processing amount calculation unit 345 causes the specific irradiator 323 to irradiate the wafer 500 with irradiation light 311 and causes the light receiving unit 325 to receive the reflected light 312. Then, the processing amount calculation unit 345 calculates the processing amount (etching amount) of the wafer 500 based on the detection result introduced from the detection unit 330.

[0072] FIG. 5 is a diagram showing the functional blocks of the throughput calculation unit according to the first embodiment, in particular the configuration of the functional blocks that calculate the wafer throughput.

[0073] As shown in FIG. 5, the time series data D1 of the light intensity of each wavelength introduced from the detection unit 330 to the processing amount calculation unit 345 is first subjected to removal and correction of various noises and fluctuations by a digital signal processing unit 3451, and is then supplied to a waveform comparator 3452 as time series data D2.

[0074] For example, a low-pass filter is used to remove noise on the time axis for each wavelength. Furthermore, for example, when removing the light intensity offset for each wavelength and observing the time change in the light intensity, signal processing may be used to calculate the amount of change in the light intensity between times and a differential value. For example, the S-G method along the time axis may be used to calculate the differential value. Furthermore, for example, when there is a fluctuation in the light intensity of all wavelengths that changes at the same magnification, signal processing is applied that normalizes the light intensity of each wavelength by the average value or the sum of absolute values ​​of the light intensity of all wavelengths.

[0075] The time series data D2 input to the waveform comparator 3452 is compared with a waveform pattern database 3453, which contains pre-acquired data on the amount of light at each wavelength relative to the amount of etching. Here, the waveform comparator 3452 compares the waveform pattern database (light amount data) 3453 with the currently obtained time series data D2 to find the waveform pattern that is closest to the current pattern, and specifies the processing amount of the wafer 500 from the closest waveform pattern.

[0076] The specified processing amount D3 is stored in the etching amount storage unit 3454. The light amount data for each wavelength in the waveform pattern database 3453 is data processed by signal processing implemented by the digital signal processing unit 3451, and is preferably processed by the same signal processing as the time-series data D2. However, it does not necessarily have to be processed by the same signal processing. The etching amount storage unit 3454 transmits the processing amount time-series data D4 to the processing amount correction unit 3455.

[0077] The processing amount correction unit 3455 corrects the processing amount at each time based on the time-series change in the calculated processing amount. As an example, if the calculated time-series change in the processing amount contains fluctuations due to noise or the like, the processing amount correction unit 3455 linearly approximates the time change in the processing amount to correct the processing amount at each time. The processing amount correction unit 3455 outputs the corrected processing amount as processing amount data. For example, the processing amount correction unit 3455 outputs the corrected processing amount as processing amount data to the overall control unit 150.

[0078] In the above example, the waveform comparator 3452 and the waveform pattern database 3453 are used to determine the processing amount (etching amount) D3 using the time-series data D2, but machine learning may also be used. In this case, the time-series data D2 is input using information from the waveform pattern database 3453, a learning model or an approximation function that outputs the etching amount D3 is generated, and the etching amount D3 is calculated (estimated) using the generated learning model or approximation function.

[0079] Furthermore, in the above example, the waveform comparator 3452 determined the processing amount D3, but it may also calculate error values ​​of two or more waveforms or intensity or frequency values ​​of each waveform. For example, when calculating the error value of the entire spectrum, which is light intensity data for each wavelength, the waveform comparator 3452 calculates the error or absolute value of the light intensity for each wavelength and calculates the sum of these as the error value. For example, when calculating the error value of a specific wavelength in the spectrum, the waveform comparator 3452 calculates the error or absolute value of the light intensity for the specific wavelength and calculates the sum of these as the error value. For example, when calculating the intensity of a spectrum, the waveform comparator 3452 calculates the sum of the intensities of all wavelengths in the spectrum or the specific wavelength as the intensity value. For example, when calculating the frequency value of a spectrum, the waveform comparator 3452 performs a Fourier transform on the spectrum in the wavelength direction to calculate the oscillation frequency of the intensity in the wavelength direction as the frequency value.

[0080] Then, the overall control unit 150 performs an end point determination for the etching process of the wafer 500 based on the processing amount data thus output from the processing amount calculation unit 345. The method for determining the end point for the etching process of the wafer 500 is not particularly limited, but the following method can be given as an example.

[0081] The overall control unit 150 compares the acquired processing amount data with a predetermined target processing amount to determine whether the current processing amount has reached the target processing amount, and terminates the etching process if it determines that the current processing amount has reached the target processing amount.

[0082] The plasma processing apparatus 100 according to the first embodiment described above makes it possible to constantly measure reflected light from the processing target area regardless of the pattern layout of the wafer 500. As a result, it is possible to achieve highly accurate measurement of the processing amount (film thickness measurement) and determination of the end point of wafer processing. Consequently, it is possible to achieve highly accurate processing of devices.

[0083] Furthermore, in the plasma processing apparatus 100 according to embodiment 1, the processing amount of the wafer 500 is measured based on the detection results of the reflected light 312 at the monitor position within the processing target area, and therefore, the processing amount can be measured and the end point of the wafer processing can be determined with higher accuracy.

[0084] 6A is a diagram showing the spectrum of reflected light from the electronic circuit portion of the wafer in embodiment 1, and FIG. 6B is a diagram showing the spectrum of reflected light from the peripheral portion of the wafer in embodiment 1. As can be seen from FIGS. 6A and 6B, the spectrum of reflected light 312 varies depending on the acquisition position of reflected light 312. That is, the spectrum of reflected light 312 from electronic circuit portion 501, which is the processing target area (FIG. 6A), differs from the spectrum of reflected light 312 from peripheral portion 503, which is outside the processing target area (FIG. 6B). Therefore, it is preferable to measure the throughput of wafer 500 based on reflected light at a monitor position within electronic circuit portion 501, which is the processing target area.

[0085] In this embodiment, the throughput of the wafer 500 is measured using the reflected light 312 reflected at the monitor position P21 or P24 located within the electronic circuit unit 501 as described above. As a result, the spectrum observed during the etching process has a shape equivalent to that shown in FIG. 6A . Therefore, the throughput of the wafer 500 can be easily determined based on the spectrum of the reflected light 312, enabling highly accurate endpoint determination. Furthermore, automatic stopping of the etching process based on this endpoint determination can improve processing accuracy. Specifically, the error from the target processing dimension can be suppressed to, for example, approximately 1 nm or less.

[0086] The pattern layout of the wafer 500 described above is an example, and even with other pattern layouts, the reflected light at the monitor position closest to the processing position can be measured by controlling the reflection position (monitor position) on the wafer 500 of the reflected light 312 to be measured. Furthermore, the reflected light within the processing target area can be measured. In other words, high-precision processing can be achieved even with wafers having other pattern layouts.

[0087] Although the present embodiment uses so-called spectrum matching as a method for determining the processing amount (etching amount), the method for determining the processing amount is not particularly limited. For example, the processing amount may be determined using light intensity data of a specific wavelength in the spectrum or feature amount data extracted from the spectrum.

[0088] Although the present embodiment uses one monitor position, multiple monitor positions may be used. In this case, for example, an average spectrum during processing is measured at multiple monitor positions. This allows for measurement of the throughput, i.e., film thickness and depth measurement (estimation), using information on the average processing state of the processing distribution within the surface of the wafer 500.

[0089] In this embodiment, the processing amount detector 340 included in the processing amount measuring device 300 detects the processing amount of the wafer 500 due to the etching process, but for example, the overall control unit 150 may detect the processing amount of the wafer 500. That is, the plasma processing apparatus 100 includes the processing amount detector 340 in addition to the overall control unit 150, but the overall control unit 150 may also function as the processing amount detector 340.

[0090] 7 is a diagram showing a schematic diagram of the positional relationship between the light emitting unit and the light receiving unit according to the second embodiment, as viewed from above the processing chamber. FIG. 8 is a diagram showing a wafer processing position and a monitor position according to the second embodiment.

[0091] In the first embodiment, an example was described in which the irradiators 323 of the light irradiation unit 321 were arranged in a row. In contrast to this, in the second embodiment, as shown in Fig. 7, the plurality of irradiators 323A constituting the light irradiation unit 321A are arranged in a two-dimensional plane. In other words, the plurality of irradiators 323A constituting the light irradiation unit 321A are arranged in multiple rows on the optical system installation surface 600. The rest of the configuration is the same as in the first embodiment, and therefore description thereof will be omitted. Note that the optical system installation surface 600 refers to the plane on which the optical system 320 is installed.

[0092] In this embodiment, the light irradiation unit 321A includes 36 irradiators 323A. These irradiators 323A are arranged in a two-dimensional plane. Specifically, 12 irradiators 323A are arranged in three rows on the optical system installation surface 600.

[0093] In this way, by arranging a plurality of illuminators 323A in a two-dimensional plane, it is possible to increase the number of monitor positions that can be selected by the optical system 320. In other words, by arranging a plurality of illuminators 323A in a two-dimensional plane, it is possible to increase the number of monitor positions that can be irradiated with the irradiation light 311 via the optical system 320.

[0094] In the first embodiment, the optical system 320 can select six monitor positions, P21 to P26 (see FIG. 4). In contrast, in the second embodiment, the optical system 320 can select twelve monitor positions, P21 to P32, as shown in FIG. 8. Therefore, the optical system condition determination unit 343 can determine a more appropriate monitor position and the corresponding irradiator 323A for the processing positions P11 to P18 on the wafer 500.

[0095] The optical system condition determination unit 343 compares the coordinates of the processing positions P11 to P18 on the wafer 500 with the coordinates of the monitor positions P21 to P32, and extracts the combination with the shortest distance between the coordinates, as in the first embodiment. For example, in the example of Fig. 8, the combinations with the shortest distance between the coordinates are the combination of the processing position P15 and the monitor position P27, and the combination of the processing position P17 and the monitor position P30.

[0096] Then, the processing amount calculation unit 345 controls the light irradiation unit 321 of the optical system 320 and the like so that the reflection position of the reflected light 312 is the monitor position P27 or the monitor position P30. That is, the processing amount calculation unit 345 estimates the film thickness and depth (estimates the etching amount) during the etching process and determines the end point of the etching process based on the detection result of the reflected light 312 reflected at the monitor position P27 or the monitor position P30.

[0097] As a result, similar to the first embodiment, it is possible to improve the accuracy of measurement of the etching amount and determination of the end point, and in turn to realize high-precision processing of devices.

[0098] 8, it is considered that the monitor positions P21, P24, P27, and P30 are within the electronic circuit portion 501, which is the region to be machined. For this reason, by irradiating light from a plurality of irradiators 323A so that the spectra of reflected light 312 from the monitor positions P21, P24, P27, and P30 are simultaneously detected by the light receiving portion 325, it is possible to realize more appropriate endpoint determination based on the average machining status of the plurality of electronic circuit portions 501.

[0099] 9 is a diagram showing a schematic diagram of the positional relationship between a light emitting unit and a light receiving unit according to the third embodiment, as viewed from above the processing chamber. FIG. 10 is a diagram showing an example of a wafer processing position and a monitor position according to the third embodiment.

[0100] The plasma processing apparatus 100 according to the third embodiment includes a plurality of irradiators 323B each configured with a lens-integrated LED as a light irradiation unit 321B constituting the optical system 320. The other configurations are the same as those of the second embodiment, and therefore, description thereof will be omitted.

[0101] 9, the light irradiation unit 321B is composed of 48 lens-integrated LEDs, which are arranged on the optical system installation surface 600. That is, in the third embodiment as well, the plurality of irradiators 323B are arranged in a two-dimensional plane.

[0102] In this embodiment, the processing position information acquisition unit 341 acquires, as information on the processing target area, coordinate information of the four corner positions P51a to P51d of the approximately rectangular electronic circuit unit 501, as shown in Figure 10, as processing position information, and supplies this to the optical system condition determination unit 343.

[0103] The optical system condition determination unit 343 selects, from among the multiple monitor positions, a monitor position whose distance to the electronic circuit unit 501 defined by the coordinates of positions P51a to P51d is closer than a preset distance, more preferably, a monitor position whose distance to the electronic circuit unit 501 is the shortest. Even more preferably, the optical system condition determination unit 343 selects a monitor position located within the electronic circuit unit 501.

[0104] 10, the electronic circuit portion 501, which is the processing target region of the wafer 500, is defined as a range specified by positions P51a to P51d. In addition, in the example shown in Fig. 10, the monitor positions that the optical system 320 can select near the electronic circuit portion 501 are monitor positions P31 to P42.

[0105] The optical system condition determination unit 343 compares the range of processing positions defined by positions P51a to P51d with the monitor positions P31 to P42, and determines monitor positions included in the processing target area, that is, the electronic circuit unit 501. In the example shown in Fig. 10, three monitor positions P34, P35, and P36 are determined as monitor positions included in the electronic circuit unit 501.

[0106] By measuring the etching amount (film thickness during etching) and determining the end point of the process based on the detection results of the reflected light 312 reflected at the monitor positions P34, P35, and P36 determined in this manner, it is possible to achieve high accuracy in the measurement of the etching amount and the determination of the end point of the process, as in the above-described embodiment, and ultimately to realize high-accuracy processing of devices.

[0107] (Embodiment 4) Embodiment 4 is an example in which, in the configuration of embodiment 1, coordinates of a measurement position of an inspection device, which is an external device, are used as processing position information of the wafer 500. Since the rest is the same as embodiment 1, a description thereof will be omitted here.

[0108] The wafer 500 to be processed by the plasma processing apparatus 100 is etched by the wafer processor 200, and then the processed shape is measured by an electron microscope.

[0109] Although not shown in the figure, the plasma processing apparatus 100 is communicably connected to an electron microscope via a cable, etc. A processing position information acquisition unit 341 acquires the measurement position of the processing shape by this electron microscope, and supplies the acquired measurement position to an optical system condition determination unit 343 as processing position information.

[0110] For example, in the example shown in Figure 4, if the position where the processing shape is measured by the electron microscope corresponds to processing position P13 on the wafer 500, the processing position information acquisition unit 341 acquires the coordinates of the processing position P13 as processing position information and supplies the acquired processing position information to the optical system condition determination unit 343.

[0111] The plasma processing apparatus according to the fourth embodiment can also achieve high accuracy in measuring the processing amount and determining the end point of the processing, similar to the above-described embodiments, and thus can realize high-accuracy processing of devices.

[0112] Fifth Embodiment The fifth embodiment is an example in which the optical system condition determination unit 343 determines the irradiator 323 that will irradiate light based on the results of trial irradiation by the light irradiation unit 321. Other than that, the fifth embodiment is the same as the first embodiment, and therefore description thereof will be omitted here.

[0113] More specifically, in the plasma processing apparatus 100 according to the fifth embodiment, prior to etching the wafer 500, a test irradiation is performed on the wafer 500 via each irradiator 323 of the light irradiation unit 321. Then, the optical system condition determination unit 343 determines the irradiator 323 to be used for processing amount measurement based on the spectrum of the reflected light 312 acquired by this test irradiation. For this reason, in this embodiment, information on the processing position is not supplied from the processing position information acquisition unit 341 to the optical system condition determination unit 343.

[0114] For example, in the example shown in FIG. 4, test irradiation is performed on monitor positions P21 to P26 within individual pattern 505 on wafer 500, and the spectrum of reflected light 312 reflected at these monitor positions P21 to P26 is acquired, and the results are shown in FIG. 11.

[0115] 11 , the shape of the spectrum of the reflected light 312 differs at each of the monitor positions P21 to P26. In the fifth embodiment, the optical system condition determination unit 343 compares the spectrum of the reflected light 312 at each of the monitor positions P21 to P26 with a preset reference spectrum, and determines the monitor position that provides a spectrum that is closest to the reference spectrum. In this embodiment, the reference spectrum is the spectrum of the reflected light at the processing position. Therefore, the monitor position in this embodiment determined in this manner can be said to be the monitor position closest to the processing position or processing region of the wafer 500.

[0116] The plasma processing apparatus according to the fifth embodiment can also achieve high accuracy in measuring the processing amount and determining the end point of the processing, similar to the above-described embodiments, thereby realizing high-accuracy processing of devices.

[0117] In the present embodiment, an example has been described in which the spectrum of reflected light at the processing position is set as the reference spectrum. However, the reference spectrum does not necessarily have to be the spectrum of reflected light at the processing position, and can be the spectrum of reflected light at any position on the wafer 500.

[0118] As described above, in this embodiment, an example has been described in which the processing volume detection unit 343 selects, from among a plurality of irradiators 323, the irradiator 323 having the closest distance between the reflection position on the wafer 500 where the light irradiated from the irradiator 323 is reflected and the processing position on the wafer 500.

[0119] However, the processing amount detection unit 343 does not necessarily have to select the irradiator 323 that is closest in distance to the reflection position of the wafer 500 and the processing position of the wafer 500. The processing amount detection unit 343 may determine the irradiator 323 that will irradiate light from among the plurality of irradiators 323 based on the difference between information on each reflection position on the wafer 500 where light irradiated from each of the plurality of irradiators 323 is reflected and information on the processing position of the wafer 500.

[0120] (Embodiment 6) Embodiment 6 is an example in which the monitor position is determined from the signal intensity based on the result of the test irradiation in embodiment 5. Other than that, it is the same as embodiment 5 described above, and therefore the description will be omitted.

[0121] More specifically, in this embodiment, the optical system condition determination unit 343 calculates an error value between the spectrum of the reflected light 312 at each monitor position obtained by test irradiation and the reference spectrum, and determines the monitor position based on the error value. The error value is calculated as the sum of the absolute error values ​​for each wavelength of the spectrum.

[0122] 12 is a diagram showing an example of the calculation results of the error value between the spectrum of reflected light at each monitor position and the reference spectrum in embodiment 6. In the graph of Fig. 12, the horizontal axis represents the coordinate of the monitor position, and the vertical axis represents the error value.

[0123] The smaller the error value of the spectrum of the reflected light 312, the closer it is to the reference spectrum and the higher the signal strength (the lower the noise). Therefore, in the example shown in Figure 12, the reflected light at monitor position P21, which has the lowest error value, is determined to have the highest signal strength. This monitor position P21 is then determined to be the monitor position used for film thickness and depth estimation and endpoint determination.

[0124] The plasma processing apparatus according to the sixth embodiment can also achieve high accuracy in measuring the processing amount and determining the end point of the processing, similar to the above-described embodiments, thereby realizing high-accuracy processing of devices.

[0125] In this embodiment, the signal intensity is calculated based on the error value from the reference spectrum, but the method of calculating the signal intensity is not limited to this. For example, if the reflectance of the processed position on the wafer 500 is high and the reflectance of other portions is low during test irradiation, the signal intensity may be the intensity value that is the sum of the intensities of each wavelength in the spectrum of the reflected light obtained by the test irradiation.

[0126] Furthermore, for example, if the spectrum of the reflected light reflected at the processing position on the wafer 500 has vibrations in the light intensity in the wavelength direction due to a thick transparent film, but no vibrations in the light intensity in the wavelength direction in other parts, the signal intensity may be calculated using a frequency value that is the frequency of the vibrations in the light intensity in the wavelength direction of the spectrum obtained by trial irradiation.

[0127] In this case, the signal strength can be defined as the amount of error of the frequency value from the target. Specifically, the monitor position where the amount of error is smallest is determined as the monitor position where the signal strength is highest.

[0128] Although the technology of the present disclosure has been specifically described above based on the embodiments, it goes without saying that the technology of the present disclosure is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the present disclosure. Furthermore, for example, the above embodiments have been described in detail to clearly explain the technology of the present disclosure, and the technology is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of the above embodiments with other configurations.

[0129] 100: Plasma processing apparatus 150: Overall control unit 200: Wafer processing device 201: Plasma 203: Processing chamber 205: Vacuum container 207: Sample stage 209: Window member 211: Shower plate 211a: Gas introduction hole 213: Exhaust port 215: Vacuum pump 217: Exhaust amount adjustment valve 219: Electric field / magnetic field forming unit 221: Waveguide 223: Electric field generation power supply 225: Magnetic field generating coil 227: Cavity 300: Processing amount measuring device 310: Light source unit 311: Irradiation light 312: Reflected light 320: Optical system 321: Light irradiation unit (multipoint irradiation port) 323: Irradiator (irradiation optical port) 325: Light receiving unit (light receiving port) 330: Detection unit 340: Processing amount detection unit 341: Processing position information acquisition unit 343: Optical system condition determination unit 345: Processing amount calculation unit 3451: Digital signal processing unit 3452: Waveform comparator 3453: Waveform pattern database 3454: Etching amount storage unit 3455: Processing amount correction unit 500: Wafer (semiconductor wafer) 501: Electronic circuit unit 503: Peripheral unit 505: Individual pattern 600: Optical system installation surface

Claims

1. A plasma processing apparatus comprising: a processing chamber inside a vacuum vessel; and a sample stage disposed in the processing chamber and on which a wafer to be processed is placed, the plasma processing apparatus further comprising: a light irradiation section having a plurality of irradiators which irradiate light to different positions on a surface of the wafer placed on the sample stage; a light receiving section which receives light reflected by the wafer from the light irradiated from the plurality of irradiators; and a processing amount detection section which detects the amount of processing of the wafer based on information obtained from the reflected light received by the light receiving section during processing of the wafer, the processing amount detection section determining an irradiator from the plurality of irradiators which will irradiate light based on the difference between information on each reflection position of the wafer where the light irradiated from each of the plurality of irradiators is reflected and information on the processing position of the wafer, and detecting the amount of processing of the wafer using the determined irradiator.

2. A plasma processing apparatus as described in claim 1, wherein the processing amount detection unit selects an irradiator from among the plurality of irradiators, the distance between the reflection position of the wafer where the light irradiated from the irradiator is reflected and the processing position of the wafer being closer than a preset distance, and detects the processing amount of the wafer using the selected irradiator.

3. A plasma processing apparatus as described in claim 2, wherein the processing amount detection unit selects from among the plurality of irradiators an irradiator having a shortest distance between a reflection position on the wafer where the irradiated light from the irradiator is reflected and a processing position on the wafer, and detects the processing amount of the wafer using the selected irradiator.

4. A plasma processing apparatus according to claim 2, wherein the processing amount detection unit calculates the distance between the reflection position and the processing position on the wafer based on the coordinates of the processing position and the coordinates of the reflection position on the surface of the wafer.

5. A plasma processing apparatus as claimed in claim 1, wherein the processing amount detection unit selects the irradiator to be used for detecting the processing amount of the wafer based on a result of comparing the spectrum of the reflected light received by the light receiving unit with a preset reference spectrum.

6. A plasma processing apparatus according to claim 1, wherein each of said irradiators is composed of a lens and an optical fiber.

7. The plasma processing apparatus according to claim 1, wherein each of said irradiators has an LED light source.

8. A plasma processing method using a plasma processing apparatus having: a processing chamber inside a vacuum vessel; a sample stage arranged in the processing chamber and on which a wafer to be processed is placed; a light irradiation section having a plurality of irradiators which irradiate light to different positions on a surface of the wafer placed on the sample stage; and a light receiving section which receives light reflected by the wafer from the light irradiated from the plurality of irradiators, wherein the method determines an irradiator from among the plurality of irradiators which will irradiate light based on the difference between information on each reflection position on the wafer where the light irradiated from each of the plurality of irradiators is reflected and information on a processing position on the wafer, detects a processing amount of the wafer using the determined irradiator, and controls the processing of the wafer based on the detected processing amount.

9. A plasma processing method according to claim 8, comprising the steps of: selecting an irradiator from among the plurality of irradiators, the distance between a reflection position on the wafer where light irradiated from the irradiator is reflected and a processing position on the wafer being closer than a preset distance; and detecting the processing amount of the wafer using the selected irradiator.

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